1. Field of the Disclosure
This disclosure relates in general to methods of synthesis of fluorinated olefins.
2. Description of the Related Art
The fluorocarbon industry has been working for the past few decades to find replacement refrigerants for the ozone depleting chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) being phased out as a result of the Montreal Protocol. The solution for many applications has been the commercialization of hydrofluorocarbon (HFC) compounds for use as refrigerants, solvents, fire extinguishing agents, blowing agents and propellants. These new compounds, such as HFC refrigerants, HFC-134a and HFC-125 being the most widely used at this time, have zero ozone depletion potential and thus are not affected by the current regulatory phase-out as a result of the Montreal Protocol.
In addition to ozone depleting concerns, global warming is another environmental concern in many of these applications. Thus, there is a need for compositions that meet both low ozone depletion standards as well as having low global warming potentials. Certain hydrofluoroolefins are believed to meet both goals. Thus there is a need for manufacturing processes that provide halogenated hydrocarbons and fluoroolefins that contain no chlorine that also have a low global warming potential.
There is also considerable interest in developing new refrigerants with reduced global warming potential for the mobile air-conditioning market.
HFC-1234yf (CF3CF═CH2) and HFC-1234ze (CF3CH═CHF), both having zero ozone depletion and low global warming potential, have been identified as potential refrigerants. U. S. Patent Publication No. 2006/0106263 A1 discloses the production of HFC-1234yf by a catalytic vapor phase dehydrofluorination of CF3CF2CH3 or CF3CHFCH2F, and of HFC-1234ze (mixture of E- and Z-isomers) by a catalytic vapor phase dehydrofluorination of CF3CH2CHF2. U.S. Patent Publication No. 2007/0197842 discloses the production of HFC-1234yf by a catalytic vapor phase dehydrohalogenation of CF3CFClCH3 over a catalyst of activated carbon, Pd on C, Pt on C or Ni mesh. U.S. Patent Publication No. 2009/0030247 discloses the production of HFC-1234yf by a catalytic vapor phase dehydrochlorination of CF3CFClCH3 over a catalyst of CsCl and MgF2.
There is a continuing need for more selective and efficient manufacturing processes for the production of HFC-1234yf